Military

Further Reading

J57

Pratt & Whitney, many years behind Westinghouse and General Electric in acquiring turbojet expertise, began to dominate the turbojet industry after its development of the JT3 (J57). The JT3 initially had better fuel economy and more than double the thrust of its competitors. The innovative design feature of Pratt & Whitney's engine was an axial compressor with a double shaft (also called a dual-rotor or two-spool), a feature that dramatically increased the efficiency of the compressor. This engine placed the company in the forefront of aircraft propulsion development. The J57 eventually powered the B-52, YB-60, F-l00, F-l0l, YF-l05A, KC-135, Boeing 707, F4D, and A3D, as well as the Snark missile

In March 1951 Pratt & Whitney began flight tests of its new 10,000-pound thrust J57 jet engine. The first two-spool turbojet engine in the world, the J57 achieved supersonic speed on a YF-100. The J57 featured a dual-rotor axial-flow compressor which allowed low fuel consumption over a wide operating range and improved the sluggish acceleration previously characteristic of jet engines. The control system of the J57 consisted of a hydromechanical fuel control (HMFC or HMC) for dry-engine combustion chambers, a HMFC for the afterburner, and separate anti-ice and ignition controls. The J57 production engine was the world's first jet engine to develop 10,000 lbs. thrust.

It evolved from the T45 turboprop engine designed for the XB-52 program. Built originally by the Boeing Company, the NASA B-52 is powered by eight Pratt & Whitney J57-19 turbojet engines, each of which produce 12,000 pounds of thrust. As advances in the B-52 design dictated greater power requirements, the turboprop concept was discarded and the wasp-waisted J57 turbojet was developed. By 1949 the J57 turbojet engine (which made commercial jet transport economically feasible) demonstrated good specific fuel consumption.

This turbojet engine was used in three of the Century Series fighters (the F-100, F-101, and F-102). The Northrop XSM-62A Snark's propulsion consisted of One Pratt & Whitney J57-P-17 turbojet engine (10,500 lbs thrust); 2 Aerojet General solid-fuel booster rockets (130,000 lbs thrust each).

Fairchild, Bell, and Martin studied high-altitude reconnaissance airplanes in design studies conducted for the Air Force during the second half of 1953. All three used Pratt & Whitney J57-P19 engines. The Bell (X-16) and Martin (B57-D) designs were chosen for development, but only the latter was completed and flew as the RB-57F. The X-16 was the most blatant misuse of the X-vehicle designation system-it was simply an attempt to hide what would today be called a spy-plane. The X-16 was designed to be a high-altitude long-range reconnaissance aircraft. None were completed before the Lockheed U-2 successfully demonstrated its ability to perform the spy mission. The first X-16 was reportedly over 80 percent complete when it was cancelled. Although never built, the X-16 pioneered several notable advances in lightweight structure design, and also was the driving force behind the development of high-altitude versions of the J57 jet engine that would go on to power the U-2 and other aircraft. The U-2 was initially powered by the Pratt & Whitney J57-P-37A of 11,000 lbs. thrust, though later replaced by the more powerful J75-P-13 of 17,000 lbs. thrust for later models.

F-8 aircraft were built originally for the U.S. Navy by LTV Aerospace of Dallas, Texas. The aircraft had a wingspan of 35 feet, 2 inches; was 54 feet, 6 inches long; and was powered by a Pratt & Whitney J57 turbojet engine.

The KC-135's original J57 engines were "smokers," especially when water was injected to increase thrust. The J57, a great engine when introduced in the late 1950s, produced 13,700 pounds of thrust, while the CFM-56 produced approximately 22,000 pounds, an increase of almost 40 percent, along with improved specific fuel consumption. With increased performance, the CFM- 56 engines transformed the KC-135 into a new airplane.

Thrust reversers haven't been around very long in the history of aviation. For the first 50 years airplanes were relatively light and they had big propellers out front which can add a lot of drag (or negative thrust) to help with stopping on the ground. With the emergence of large jet-powered aircraft in the late 1950s and early 1960s the problem of stopping was a serious engineering challenge. Engineers developed the thrust reverser systems of sliding sleeves and clamshell doors in the 1950s. The first two major engines to use this technology were the Pratt & Whitney JT-3 (Military J57) and the General Electric CJ805 (derived from the Military J79). The basic idea is to route the primary jet and fan section bypass air through a series of chutes and doors to propel it forward. These devices were complicated "Rube Goldberg" devices that had a lot of reliability and maintainability problems.